ISO 22553-7-2020, Paints and varnishes – electrodeposition coatings – Part 7: Wet film resistance

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ISO 22553-7-2020, Paints and varnishes – electrodeposition coatings – Part 7: Wet film resistance

Wet film resistivity provides information about the deposition behavior of electrodeposited coatings, that is, information about film thickness and film thickness variation, homogeneous plating capacity, and possibly deposition properties under specific conditions.

1 Scope of application
This document specifies a method for determining the resistivity of wet films of electrodeposited coatings (e-coat) for the automotive industry and other general industrial applications (e.g. cooling units, consumer products, radiators, aerospace, agriculture).

2 Normative reference files
When the following documents are referenced in the context, part or all of them constitute the requirements of this document. For dated references, citation-only versions apply. For undated citations, the most recent version of the referenced document (including any amendments) applies.

ISO 1514, Paints and varnishes — Standard plates for testing

ISO 4618, Paints and varnishes – Terms and definitions

ISO 22553-1, Paints and varnishes – electrodeposited coatings – Part 1: Vocabulary

ISO 23321, Paints and varnishes solvents – softening water for industrial applications – Specification and test methods

3 Terms and Definitions
For the purposes of this document, the terms and definitions given in ISO 4618, ISO 22553-1 and below apply.

3.1 Resistance R

The ratio of the potential difference along a conductor to the current through it

Entry Note 1: Resistance is given by Ohm’s law as shown in formula (1) :

u is the potential difference;

I is current.
The unit of resistance is ohm (Ω), given by the following formula:

Resistance depends on the material, size (length and cross section) and temperature of the conductor.

[Source: ISO 15091:2019, 3.1]

3.2 Resistivity ρ

Cross-sectional area The resistance per unit length of a material

Item Note 1: Resistivity is given by formula (2) :

A is the cross-sectional area of the conductor;

I is the length of the conductor.
Resistivity is measured in ohms · meters (Ω·m).

[Source: ISO 15091:2019, 3.2]

3.3 Wet film resistance Rw

Measure the total resistance (3.1) of electrodeposited coatings, including substrates, pretreatments, and other coatings

Note 1: When measuring resistance, technical measurement conditions also have an effect, e.g. membrane, measuring electrode.

Note 2 The unit of wet film resistance is ohm (Ω).

3.4 Dynamic wet film resistance

The measured total resistance (3.1) of the electrodeposited coatings (including substrates, pretreatments, and other coatings) is a function of deposition time

Note 1 The unit of wet film resistance (3.3) is ohm (Ω).

3.5 Electrostatic wet film resistance

Measure the total resistance (3.1) of the electrodeposited coatings, including substrates, pretreatments and other coatings read out at the end of deposition time

Note 1 The unit of wet film resistance (3.3) is ohm (Ω).

3.6 Wet film resistivity ρw

The wet film resistance (3.3) is multiplied by the electrode area relative to the distance between the electrodes

Note 1: Wet film resistivity is given by formula (3) :

Rw is wet film resistance;

A is the area of the electrode;

l is the length of the conductor.
The unit of wet film resistivity is ohm ·m (Ω·m).

3.7 Electrical conductivity γ

Reciprocal of resistivity (3.2)

Note 1: The conductivity is given by formula (4) :

The unit of conductivity is Siemens · m-1 (S · m-1).

[Source: ISO 15091:2019, 3.4]

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